On the seafloor of the shallow coastal regions north of Siberia, microorganisms produce methane when they break down plant remains. If this greenhouse gas finds its way into the water, it can also become trapped in the sea ice that forms in these coastal waters. As a result, the gas can be transported thousands of kilometres across the Arctic Ocean and released in a completely different region months later. This phenomenon is the subject of an article by researchers from the Alfred Wegener Institute, published in the current issue of the online journal Scientific Reports. Although this interaction between methane, ocean and ice has a significant influence on climate change, to date it has not been reflected in climate models.
On the seafloor of the shallow coastal regions north of Siberia, microorganisms produce methane when they break down plant remains. If this greenhouse gas finds its way into the water, it can also become trapped in the sea ice that forms in these coastal waters. As a result, the gas can be transported thousands of kilometres across the Arctic Ocean and released in a completely different region months later. This phenomenon is the subject of an article by researchers from the Alfred Wegener Institute, published in the current issue of the online journal Scientific Reports. Although this interaction between methane, ocean and ice has a significant influence on climate change, to date it has not been reflected in climate models.
In August 2011, the icebreaker Polarstern from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) was making its way through the ice-covered Arctic Ocean, on a course that took her just a few hundred kilometres from the North Pole. Back then, AWI geochemist Dr Ellen Damm tested the waters of the High North for the greenhouse gas methane. In an expedition to the same region four years later, she had the chance to compare the measurements taken at different times and found significantly less methane in the water samples.
Ellen Damm, together with Dr Dorothea Bauch from the GEOMAR Helmholtz Centre for Ocean Research in Kiel and other colleagues, analysed the samples to determine the regional levels of methane, and the sources. By measuring the oxygen isotopes in the sea ice, the scientists were able to deduce where and when the ice was formed. To do so, they had also taken sea-ice samples. Their findings: the ice transports the methane across the Arctic Ocean. And it appears to do so differently every year, as the two researchers and their colleagues from the AWI, the Finnish Meteorological Institute in Helsinki and the Russian Academy of Science in Moscow relate in the online journal Scientific Reports.
Read more at Alfred Wegener Institute, Helmholtz Centre For Polar and Marine Research
Photo: AWI sea-ice physicists have ericted an ice camp to investigate melt ponds on Arctic sea ice. (CREDITS: Alfred-Wegener-Institut / Mar Fernandez)
